Tips and Thoughts on Mobile WebVR Development

I have been involved in a few VR projects this last year. While the earlier prototypes used Unity as the development environment, some of the new ones use WebVR, an emerging web standard for VR development.

WebVR, as opposed to native-app VR, does have a few advantages:

JavaScript tooling is pretty good and getting better

Automatically falls back to an in-browser 3D experience on non-VR devices

Not having to compile the app to quickly check the changes in a browser is pretty awesome

The biggest thing though is that the kind of experiences we have always thought about: moving from one VR experience, is not possible in a series of native apps. I have heard the future of VR referred to as a “web of connected VR experiences” and that is the vision that is truly exciting.

Cyberspace as imagined by Ghost in the Shell

That said, current tooling is much better for VR native apps with most tools focusing on Unity, which is really the de-facto tool for game developers. However I really hope the tooling on WebVR side starts getting better.

Developing for WebVR

The way we currently build for WebVR is by using AFrame, a VR framework built on top of WebGL primarily maintained by Mozilla and the WebVR community. AFrame is built on top of ThreeJS, the most popular 3D library for WebGL. For desktop VR development, the only desktop browser that you don’t have to finagle with too much is Firefox. Most of the development is done on Oculus Rifts connected to some beefy PCs.

Current State of WebVR support

Another tool worth noting is Glitch which provides instant development setups for JavaScript based apps. Glitch has been very useful to quickly try out an idea and share it internally. The develop -> preview flow is pretty straight forward.

The developer workflow for mobile VR development though is a different story. While our current prototype had no requirements to be mobile, I recently tried it on a Google’s Daydream and found a few bugs. Fixing those seemed trivial, but actually doing that was a lot more painful than I would have thought. Here are some problems I ran into:

Cannot start a WebVR experience from inside VR

Currently there is no available web browser that can launch from the DayDream VR home menu. While Chrome on Android supports WebVR and will trigger a “Insert into Headset” DayDream action when a user taps on a VR button on a WebVR experience, there is no way to get to that experience from within DayDream itself. You cannot pin a WebVR experience to your DayDream Home and WebVR experiences don’t appear in your recent VR apps section.

This is actually really frustrating. The workflow to debug a DayDream error is:

Fix(?) bug

On phone, go to Chrome, launch app

Tap “VR” mode

Insert phone into headset

Verify Chrome Remote Debugger is still connected

See if the bug still appears

Pop phone out of headset

The constant popping of the phone in and out of the headset get old really fast. One option may be to add a “reload” button in your WebVR experience but I am not sure if that will work, since you aren’t supposed to be able to enter VR mode without an explicit user action (like a button tap)

One thought I did have was to create an Android app with the Manifest declaring it as a DayDream app, and then have its main view just be a WebView. Unfortunately that didn’t work, though I did get the app in the DayDream Home view. A different idea was to let this app launch Chrome with my WebVR app’s URL. Again, there were challenges: For one Chrome launched in conventional view and did not automatically trigger the VR split view for the left and right lenses. To add to this hack, I added a trigger to call AFrame’s enterVR() method when the page loaded which kinda worked but every launch caused this weird blink when the app went from 2D to VR mode that it was actually painful to use.

One HUGE tip in this workflow: Make sure you have enabled the DayDream debug menu selected the “Skip VR Entry Screens” without which the workflow mentioned adds like 2 more steps per debug.

Using Chrome Remote Debug

For a lot of my testing, all I needed was the console.log function from developer tools. You can see your logs using Chrome Developer Tools’ Remote Debug feature. Not sure I was doing it wrong but I kept losing connection to the active tab every time I reloaded the page to check. Really annoying. At the end of the day, I did discover the A-Frame Log Component, which I haven’t used yet, but intend to very soon.

Lack of a DayDream Controller Emulator

If you are developing for VR, your productivity is directly proportional to how much of the development you can do without putting on the headset. With WebVR, since your app automatically works in a browser, you can do a lot of development without the headset. Unfortunately this breaks down when you are trying to code around user interactions. You can use the Mouse as a raycast source which gets you partly there but you really want an emulator for the hand controllers to try different things out.

DayDream officially has an emulator for its controller, but that controller only seems to target Unity and Unreal based projects. There are other projects like DayFrame for AFrame but since my problem was specific to the DayDream controller, using a proxy emulator didn’t make much sense.

What I really wanted to do was to pair the official Google DayDream controller to my PC but I haven’t been able to find any way to do that yet.

Conclusion

I have been generally enjoying working with AFrame and it has a surprisingly (to me) strong community of active developers. However the developer workflows, esp for on-device testing, still need work. Ideally what I am looking for is a one click that deploys my WebVR app to a server and then launches DayDream pointed to the WebVR page running in fullscreen VR. Or even better, a WebVR/AFrame equivalent of Create React App or similar boilerplate projects, that automatically sets up all the best tools for developing and testing WebVR projects on both the browser and on-device.

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Author: Arpit Mathur

Arpit Mathur is a Principal Software Engineer at Comcast Labs where he is currently working on Virtual and Augmented Reality as well as investigating Blockchains and the decentralized internet.
View all posts by Arpit Mathur